Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017	Jan. 01, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017	$ 188,054
Net income	2,632	$ 4,086
Cumulative effect adjustment of adopting ASU 2014-09			$ 400		$ (396)
Adjusted balance at December 31, 2017				$ 187,658
Foreign currency translation adjustment	2,432
Repurchases of common stock	(7,261)
Stock-based compensation expense	698
Issuance of stock for employer contributions to retirement plan	711
Other	(51)
Ending Balance	$ 187,022
Stock repurchased during period, shares	312,000	70,000
Stock repurchased during period, value	$ 7,300	$ 1,700
Stock repurchase program, remaining authorized repurchase amount	4,500
Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017	172
Adjusted balance at December 31, 2017				172
Ending Balance	172
Additional paid-in capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017	107,256
Cumulative effect adjustment of adopting ASU 2014-09					0
Adjusted balance at December 31, 2017				107,256
Stock-based compensation expense	698
Issuance of stock for employer contributions to retirement plan	4
Other	(589)
Ending Balance	107,369
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017	106,599
Net income	2,632
Cumulative effect adjustment of adopting ASU 2014-09					$ (396)
Adjusted balance at December 31, 2017				106,203
Ending Balance	108,835
Treasury stock at cost
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017	(11,118)
Adjusted balance at December 31, 2017				(11,118)
Repurchases of common stock	(7,261)
Issuance of stock for employer contributions to retirement plan	707
Other	538
Ending Balance	(17,134)
Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2017	(14,855)
Adjusted balance at December 31, 2017				$ (14,855)
Foreign currency translation adjustment	2,432
Ending Balance	(12,220)
Interest Rate Cap
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in fair value of interest rate derivative instrument, net of tax	148
Interest Rate Cap | Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in fair value of interest rate derivative instrument, net of tax	148
Interest Rate Swap
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in fair value of interest rate derivative instrument, net of tax	55
Interest Rate Swap | Accumulated other comprehensive loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in fair value of interest rate derivative instrument, net of tax	$ 55